Suppression of diffusion by a weak external field in periodic potentials
Institute of Theoretical Physics, University of Tartu, 4 Tähe Street, 51010 Tartu, Estonia
Corresponding author: a email@example.com
Revised: 5 May 2005
Published online: 11 October 2005
Diffusion of overdamped Brownian particles in sawtooth potentials subject to a spatially uniform tilt is studied focusing on the influence of a small bias. It is shown that in the potentials with an asymmetry in the direction of tilting force, the application of a weak external force leads to a suppression of diffusive motion: the diffusion coefficient as a function of bias passes through a minimum which precedes an increase of diffusion caused by delocalization of particles. In the weak noise limit the effect can be understood as a competition between the forward and backward escape rates over potential barriers determining the behaviour of the diffusion coefficient in a weak external field. The asymptotic lower border for the reduction of spreading of particles at fixed temperature is established. The decrease of diffusion is accompanied by more rapid increase of current.
PACS: 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion / 05.60.-k – Transport processes / 02.50.Ey – Stochastic processes
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005